Work machines, such as mining trucks, typically include a left axle, a right axle, and a differential assembly which mechanically couples the right and left axle. The differential assembly allows the right and left axles to rotate at different speeds relative to one another as the work machine is driven in a curved path.
The differential assembly includes a right wheel group and a left wheel group. In addition, the differential assembly has an internal component chamber which houses a number of components. For example, the internal component chamber houses side gears and pinion gears. Adequate lubrication of the aforementioned components by a fluid, such as oil, is an important factor in maintaining the proper operation of the differential assembly. For example, the oil contained within the differential assembly must adequately lubricate the right wheel group and the left wheel group in order for the work machine to operate properly.
Moreover, having the oil within an appropriate predetermined temperature range is also an important factor in maintaining the proper operation of the differential assembly. For example, during cold start up conditions the oil contained within the internal component chamber must be heated to be within the appropriate predetermined temperature range. On the other hand, once the work machine begins performing various work functions, the oil must be cooled such that the oil is maintained within the predetermined temperature range.
Some differential assembly designs maintain a level of oil in the internal component chamber such that the gears contained therein are continuously in contact with the oil pooled therein. Having the gears in contact with the pooled oil results in the oil being heated due to the physical interaction between the oil and the gears. Specifically, the rotation of the gears through the pool of oil causes the temperature of the oil to rise. While rotating the gears through the pool of oil is an effective method of heating the oil, it also requires a significant amount of power. Therefore, having the gears contained within the internal component chamber of the differential assembly continuously in contact with a pool of oil results in the work machine losing a significant amount of horse power as the gears are rotated through the oil. This particularly true when the gears being rotated through the pool of oil are relatively large as is the case with mining trucks.
What is needed therefore is an apparatus and method for controlling the temperature of fluid in a differential assembly which overcomes the above-mentioned drawback.